F5 power amplifier

I got my PS built tonight for the F5. I went dual mono and used smaller transformers (bigger ones were hard to come by here). So I am pretty happy I got it all put together neatly enough. Testing now to follow.


Pics to follow too.

Another Q though:

I'm using a Tx with a single primary. How exactly should I wire in the CL60s? Should I add just one in series with the AC live or should I parallel 2 of them with one AC leg? I think they are the 5A rated ones.


Fran
 
I've been building the chassis all day and my brain isn't working now. I'm just finishing up the boards and installing the pots with the pre-adjustment.

When NP says to adjust P1 and P2 for minimums at startup I'm assuming that is zero ohms across, such that Q1/2 drains are at the rails and Vgs to outputs is 0v. Then ease into the pots (increase resistance) alternately to develop/increase voltage across R3/4. Is that correct? :scratch: Trying to avoid big smoke signals.
 
Official Court Jester
Joined 2003
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tms0425 said:
........

When NP says to adjust P1 and P2 for minimums at startup I'm assuming that is zero ohms across, such that Q1/2 drains are at the rails and Vgs to outputs is 0v. Then ease into the pots (increase resistance) alternately to develop/increase voltage across R3/4. Is that correct? :scratch: Trying to avoid big smoke signals.


correct .
 
Thanks ZM. I drove about 6 hours today, then spent the rest cutting and tapping metal and soldering pcb's. My tired head said the Mosfets couldn't wake up as long as all that was true. Once I erased the current protection parts and ignored the double feedback loops the remaining circuit is ridiculously simple so it makes sense now.

Somehow I thought I could build a chassis and the electronics in one day, but alas, maybe two it is... Like those TV shows where you have 8 hours to fabricate an entire custom motorcycle :D Crazy, those guys...
 
If most of those custom motorcycle guys were to build an amp the heatsinks would come predrilled and tapped and the pcb would be full of discrete components.
The majority of the diy audio community is truly from SCRATCH. Testing each discrete component from maybe hundreds and cutting, drilling, tapping and assembling everything with household tools.
I mean would it not be nice to have a water jet milling tool at home to fabricate with.
I await my pcb's so I can begin this nice journey in F5 territory.
So how does it sound?? This latest creation from Mr. Pass.
The quality of the one off amps built here is truly a work of art.
Thanks Nelson for the nice proven designs.
Tad
 
I'm running the amp without thermistors and few minutes ago I also removed current limiting components. I'm aiming at Figure 5 circuit, without enhancements. ;)
 

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I'm always looking for better amps and I'm using F3 in my main system for over a year now.

Today was a first day I listened to F5 (with Fertins). Initially it seemed to be a bit lean, dry and bass shy. But I liked the clarity and purity of the tone ;)

After I removed current limiting circuitry the amp became much more emotionally envolving and now it seems to have quite a potential. It's certainly cleaner that GC with better detail, although I drive it directly from a DAC (no volume control) while the GC was always played through TVC.

I would still like to have it more texture and tone density, but I hope to improve on it with better matching PS (I'm presently using IXYS bridges and 4 x 22000/40 Sikorels).

But so far I like it.
 
Peter Daniel said:
I'm always looking for better amps and I'm using F3 in my main system for over a year now.

Today was a first day I listened to F5 (with Fertins). Initially it seemed to be a bit lean, dry and bass shy. But I liked the clarity and purity of the tone ;)

After I removed current limiting circuitry the amp became much more emotionally envolving and now it seems to have quite a potential. It's certainly cleaner that GC with better detail, although I drive it directly from a DAC (no volume control) while the GC was always played through TVC.

I would still like to have it more texture and tone density, but I hope to improve on it with better matching PS (I'm presently using IXYS bridges and 4 x 22000/40 Sikorels).

But so far I like it.

Geez, I thought the F5 was supposed to sound good the way it is? It got a good review.
 
Member
Joined 2003
Paid Member
Looks a little bare. I'll try it this way too for starters. But as Nelson put it........."you are of course welcome to delete this portion of the circuit, and of course you will not complain if a shorted output lets the smoke out of your amplifier"
 

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